1. Field of the Invention
The present invention relates to a reproduction apparatus and method and, more particularly, to a reproduction apparatus and method suitable for use in a case in which, for example, digital sound data and the like recorded on a movie film is reproduced.
2. Description of Related Art
FIG. 8 shows the construction of an example of a conventional movie film. A movie film 1 is, for example, a 35 mm movie film used in movie theaters, with perforations, serving as feed holes used to obtain feeding synchronization, being formed at predetermined intervals on both end portions of the movie film along the width direction. Further, picture frames (commonly called frames) in which an image is optically recorded are formed in the central portion thereof along the width direction. Here, the length of the picture frame along the length direction is, for example, 19.05 mm, and for one picture frame, for example, four perforations are formed on both the right and the left.
Between the picture frames and perforations on the right (right perforations in FIG. 8), analog tracks are provided, an analog sound signal being formed optically therein.
Meanwhile, as CD (Compact Disc) players and other digital audio equipment have become widespread into ordinary households in recent years, there has been an increased demand for digitization of movie sound. Accordingly, recently a technique is becoming popular in which digital sound, in addition to analog sound, is recorded on a movie film, and digital sound is normally used and analog sound is used as a back-up.
Various methods of recording digital sound on a movie film have been proposed. As one of them, there is a SDDS (Sony Dynamic Digital Sound) (trademark) method in which, as shown in FIG. 8, a P track or a S track is provided on the side further to the left of the left perforations or on the side further to the right of the right perforations, and pits in the form of dots are formed therein, thus recording digital sound. In the SDDS method, for example, as shown in FIG. 9, rectangular pits (dots), which are 24 microns along the width direction and 22.5 microns along the length direction, are recorded optically in a manner corresponding to digital sound. The pitch along the length direction is, for example, 26.5 microns.
Reproduction of the P tracks and the S tracks in which digital sound is recorded is performed, for example, along the length direction with a pit sequence formed along the width direction being one unit.
FIG. 10 shows the principle of the reproduction method for reproducing digital sound. For example, light emitted from a light source, for example, an LED (light-emitting diode) 101 or a halogen lamp, is radiated on the P tracks and the S tracks of the movie film 1 via an optical fiber 102. The light radiated onto the P tracks and the S tracks passes therethrough in a manner corresponding to the pits formed therein, and the transmitted light enters a lens 103. The transmitted light from the movie film 1 is converged by the lens 103 onto line sensors 104, such as a line CCD (charge coupled device). In the line sensors 104, the light is photoelectrically converted into an electrical signal corresponding to dots for one line along the width direction. This electrical signal is provided to a decoder 105 whereby it is decoded into digital sound, and is output from a speaker 107 via an amplifier 106.
In the SDDS method, for example, eight-channel sound output is made possible: the screen center (center) in which an image is projected, the right and left thereof (left and right), between the center and the left (left center), between the center and the right (right center), subwoofer, left surround, and right surround.
Further, in the SDDS method, digital sound is coded by a coding method called ATRAC (Adaptive TRansform Acoustic Coding) adopted in mini-discs (trademark), achieving a data compression rate of about 1/5. In the decoder 105, decoding of data which is coded by this ATRAC method, and others is performed.
In the case where the reproduction of the P tracks and the S tracks such as that described above is performed, in order that the reading characteristics are maintained to some degree, it is required that the light-amount distribution in the line sensors 104 be uniformly formed. Here, the formation of a uniform light-amount distribution refers to the output of the line sensors 104 becoming almost uniform as shown in FIG. 11 when it is assumed that the entire movie film 1 is uniformly transparent. Specifically, it means that the ratio of the minimum output to the maximum output (minimum output/maximum output) in a particular line of the line sensors 104 becomes a predetermined standard value or more.
In order to cause the S/N (Signal/Noise) ratio of the line sensors 104 to be a predetermined value or more, the amount of light which reaches each pixel of the line sensors 104 must be nearly constant regardless of the pixel position of the line sensors 104.
Also, the movie film 1 is constructed in such a way that a layer of emulsion is formed on a base, as shown in FIG. 12A, and pits as digital sound are formed by optically discoloring the emulsion. Since the projection thereof is performed by causing the movie film 1 to be fed along the length direction, as shown in FIG. 12B, a number of fine scratches which are extended along the length direction are ordinarily formed on the base. In order to prevent (reduce) an occurrence of pit reading errors due to these scratches, it is required that the light to be radiated onto the movie film 1 be diffuse light.
Conventionally, because of the above, an illumination optical system of a reproduction apparatus which reproduces digital sound is constructed as shown, for example, in the perspective view of FIG. 13.
That is, in order that the amount of light which passes through the film 1, the lens 103, and reaches each pixel regardless of the pixel position in the line sensor 104 is constant, the optical fiber 102 is constructed by using about 10,000 very small fibers having, for example, a diameter of approximately 50 mm, and these are made to branch into bundles of about 2,500 each as very small fibers 102.sub.1, 102.sub.2, 102.sub.3, and 102.sub.4. Further, the very small fibers 102.sub.1 to 102.sub.4 are arrayed, for example, in such a manner as to be twisted so that the positional relationship of both the end surfaces becomes random, thereby causing the light which exits from the optical fiber 102 to be constant.
Further, to make the light to be radiated onto the movie film 1 diffuse light, in addition to an LED 101.sub.1 which emits light which is parallel to the optical axis of the optical fiber 102, LEDs 101.sub.2 and 101.sub.3 which emit light which forms a predetermined angle, other than 0 degrees, with respect to the optical axis of the optical fiber 102 are provided so as to form light (diffuse light) having a high degree of diffusion. In this case, when light is diffused in this manner, as shown in FIGS. 14A and 14B, diffuse light having the same diffusion angle (40 degrees in FIGS. 14A and 14B) is emitted from the optical fiber 102 in both the width direction (XIVA--XIVA direction) and the length direction (XIVB--XIVB direction).
Further, it is difficult for one set of LEDs 101.sub.1 to 101.sub.3 to obtain a sufficient amount of light, and loss in the amount of light is large during input and output of light to and from the optical fibers 4. Therefore, conventionally, for example, an additional three sets of LEDs similar to LEDs 101.sub.1 to 101.sub.3 are prepared, and a total of 12 LEDs (=3.times.4 sets) are used to maintain the intensity of light.
In order to maintain the intensity of light, there is a method using, instead of an LED, for example, a halogen lamp having an intensity higher than that of an LED. However, halogen lamps generally have a drawback that their service life is shorter than that of an LED.
Therefore, conventionally, as an illumination optical system for reproducing two tracks of an S track and a P track in which digital sound is recorded, two sets of optical fibers formed of 12 LEDs and four very small fibers are required, presenting the problem that the apparatus has a higher cost and becomes enlarged.